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To All I'm not telling anyone what to do or not to dive. I'm suggesting that they take whatever cylinders they are using and see if they can swim them without the assistance of a wing such as in event of a failed BC. As I have done this for myself I know which cylinders I can swim with a failed BC. I dived 80's for years (did not like them) then went to cressi 70's at 3000 psig still my favorite ocean cylinders. They are slightly bouyant when empty(not like US steel 70's). Loved these still do, but when teaching they are not useable as I feel the instructor must insure he/she has adequate gas to share with a student who may be stressed and breath more than there normal RMV. Thus I have played with and used the Cressi 106 (same cylinders as OMS 98's). These cylinders when empty float with the bottom half of the cylinders sticking out of the fill bucket. I can and have to verify to myself swim these without the use of my BC. So I feel safe in them. I also have practiced with the 85's which is what I use most of the time now in the ocean and can and practice off and on to be sure that I can swim them thus I feel safe in these cylinders as well. What I recommended is that each person practice this(with the cylinders they currently dive) and that will allow them to discover if the cylinders they are using is safe for them. Some may find they need to change cylinders What is wrong with suggesting people do realistic self training drills to find what does and does not work for them?? The next thing I recommended was that divers practice a worse case scenario rescue in a simulated manner. this included number one allow a diver to deflate his/her BC and sink give them a slight headstart (practice in 60 to 70 feet of water and start the drill from about 15 feet let the buddy get about 20 feet below you then go after them) Catch the buddy to do so you will need to get negative and swim after them . Once you have caught them inflate your wings to see if you can first stop there descent. then stabilize the buoyancy with your BC then begin a controlled ascent using your bc, then on the surface keep both of you afloat for a reasonable time. Now try a similar drill with you being negative as as you sink remove your lift bag, attach your reel and inflate the bag, this will allow you to evaluate the effectiveness of a lift bag as a reliable backup BC Again what is wrong in having someone practice these drills to evaluate the lift of there BC's in emergencies and to verify the effectiveness of a lift bag as a back up BC?? Repeat using the lift bag as abuddy rescue device and see how well it works. Next do the surface rescue drill I described. If you have taken a recent IANTD trimix course this is now a required skill. I really do not see how anyone could object to someone practicing these. for some of you it may mean a change in cylinders for some a change in wings, and some of you may opt to go to some type of redundant BC. I generally witness some BC failure every year most of the time it is due to faulty maintenance. So far I have not WITNESSED someone getting into a problem that they have not been able to overcome. The most common failure I have seen is divers yanking on pull dumps and pulling the inflator hose lose.In my opinion tech divers should avoid pull dumps, because it is an additional failure point. What I recommend to you on the list is what I tell each of my students: 1. Go through the logic of how you configure your equipment 2. List all the advantages and any disadvantages of your equipment configuration. Be sure you address each and every part of the configuration. Drill such as the above will provide insight on the effectiveness of your current configurations with regard to cylinders and BC's Once you have done this you will be able to intelligently explain and understand why you do what you do. Unfortunately many going into tech diving do a lot of changes in config based on this is what my last instructor told me to do. or I read this is the only thing that works and the next instructor may totally change them out. Those who do the above will know why they configure as they do and will be more conservative in configurations changes until they determine the logic behind a change. If you read IANTD's new technical Diver encyclopedia there is a lot of discussion on configuration and a lot of similarity among many of the authors in how they configure. But each is a well thought out system. Below is my personal configuration. I have made one recent change and that is going from a 9 inch inflator hose to a 6 inch one. Tom Mounts Configuration The doubles are manifolded together. If available, an isolator valve is used. The regulators are placed so that all hoses extend vertically downward from the valves. The long hose is on the right post and is the primary regulator. This hose is wrapped under the wings and, when using my normal waist light placement, underneath it, the hose is simply routed behind the wings, across the body and a ¼ turn around the neck. When diving without a light, the excess hose is tucked into the waist strap. The short hose is the backup regulator. A permanently attached surgical loop is attached to the backup regulator; this goes around the neck of the diver. This second stage should be right at the base of the neck just below the chin. The SPG has a custom length of 24 inches (57.6 cm) and runs down from the regulator on the left post. It is attached to the left shoulder D-ring. The BC inflator hose coming out of the BC (wings) is a custom 9 inch (21.6 cm) hose. The power inflator hose is 15 inches (36 cm) long. This short hose arrangement is ideal for fine tuning buoyancy without a need to raise the hose or to use the lower pulldumps on the wings. The power inflator hose is attached to the left. When diving a wet suit I recommend the use a backup BC, although I do not always do so. On dry suit dives, one set of wings can be used. The dry suit serving as a backup BC. The primary light for use in cave or wreck diving is normally waist mounted. When diving in areas that are narrow, such as some sections of wrecks or constricted caves, butt mounting is a logical choice. Waist mounting is a simpler configuration for use in less constricted areas and is ideal for long hose configuration. The safety lights are mounted on the shoulder straps with one being placed on each shoulder strap. This allows ease of access to the lights while keeping them removed from busy areas and reducing drag. Reels as needed (use only what you need) are carried on the waist D- rings or on a ring attached to the backplate or back D-ring on the crotch strap. The lift bag is carried by two surgical tubing loops attached to the base of the backplate. Stage tank rigging is by having a line around the neck of the cylinder and to the point on the cylinder that will align the bottom snap with the waist D-ring. The line is covered with tubing. This can also be with stage straps. Backplate: I use a stainless steel backplate with a QD on the lower left shoulder strap. I have a back injury that flares up from time to time and the TransPac is friendlier on the back on those occasions. I also use a TransPac when traveling due to its lighter weight and ease of changing from singles to doubles. Attached to the backplate or TransPac is a continuos crotch strap that has a loop that goes around the waist strap. The crotch strap has a DPV ring at the front and a tow ring at the back of the strap. At the base of the backplate or TransPac a surgical tubing loop is at either side to allow storage of a lift bag when diving in open water. Cutting tools are carried on all dives. A pair of surgical scissors is in a holster on the waist strap. A small knife is placed on the back of my light handle for immediate access. The cylinders normally used are double 112s (17L) for cave diving and double 85s (13 L) for deep open water and wreck dives. On dives not requiring larger cylinders, I use either double 45s (7L) or single cylinders with dual valve outlets that provide sufficient volume of gas for the planned dive. -----Original Message----- From: Peter Wallace <hwallac1@ta*.rr*.co*> To: Tom Mount <TOM.MOUNT@wo*.at*.ne*> Cc: techdiver@aquanaut.com <techdiver@aquanaut.com> Date: Sunday, July 19, 1998 5:00 PM >> > -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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